Sidney geobge bbown



s. 9. BROWN.

ELECTRICAL TRANSLATING DEVICE.

APPLICATION FILED APR. IT. 1918.

Patented Oct. 14, 1919.

' SIDNEY GEORGE BROWN, 01 NORTH ACTON, ENG-LAID.

- nLEcrBIcAI. TRANSLATING nnvrcn.

Specification of Letters Patent.

Application filed April 17, 1918. Serial No. 229,099.

To all'whom it may-concern I Be it known that I, SIDNEY GEORGE BROWN, asubject of the King of Great Britain, residing at Edward Road, WillesdenLane, North Acton, England, have in vented certain new and usefulImprovements in Electrical Translatin Devices, of which the following isa speci cation.

This invention relates ,to telephone and like receivers or'relaysadapted astranslating devices for use with variable current of smallamplitude, of themtype in which a receiver.

vibratin magnetic member, such as a reed, is place in a magnetic fieldvaried by flfie received currents. The chief'objectof t e presentinvention is to construct a telephone receiver or like translatingdevice with minimumelasticity whereby clear speech is obtained owingto'the absence of resonance and to enable the strength of the magneticfield to be reatly increased, so. as to improve the efl iciency andsensitiveness of the In a receiver of this tyipeas previously employedthe magnetic eld acted transversely upon the reed so as to exert abending action and, as the stiffness of the reed was limited in order torespond to the small oscillatory changes in the field. due to thereceived current, the field itself was limited in strength in accordancewith the required elasticity of the reed.

According to this invention the magnetic field acts longitudinally uponthe vibrating member or reed, so as to exert a direct pull from its baseor point of support, while the received current has a transverse actionand' effects the vibration of the reed across the main field. Theelasticity of the reed 1s therefore independent of the magnetlc; field,which may if desired be strong enough to bring the reed or equivalent vibratlng member up to saturation point. The reed may be of laminatediron to get suflicient flexibility and may be excited by a permanentmagnet or by an electromagnet.

In order that the saidinvention may be clearly understood and readilycarried into effect, I will describe the same more fully with referenceto the accompanying drawv ings, in which p I Figures 1 and 2 showrespectively. in plan and transverse section a telephone receiverembodying my invention.

Figs. 3 and 4 are respectively an eleva netic field at the gap tioorliand a plan of a modified construction, an

Figs. 5 and 6 show two further modificatlons.

Patented Oct. 114, 19 19.

A is the vibrating reed. B is the magnet.

C is the-receiving coil.

Referring to Figs. 1 and 2 the magnet B is shown of circular form with agap at one side, on the two ends of the' magnet being secured the polepieces 12 of laminated iron, each of which is formed with the channel 6opening opposite the reed A through the narrow gap 6 .The reed A isbuilt up of two thin plates, which may be of aluminum alloy, riveted toa very-flexible and much thinner sheet a of tempered steel forming aflexible hinge or fulcrum.

Between the plates at their front end is secured a small armature abuilt u of very thin iron stampings separated by th1n copper plates. Theiron stampings may have a thickness of say 3 mils. and the separatingcopper plates a thickness of about 2 mils, the armature comprising abouteight iron stampings in the case of a reed suitable for a telephonereceiver.v The object of the"sep arating copper plates is to reduce thespread ing of the magnetic lines so that they are maintained as nearlylongitudinal as possible in the reed A. It has been found that thismethod of building up .the reed gives better regulation on the receiver.This armature lies immediately opposite the gaps b of the pole pieces b,the magnetic field passing between the poles I) through the armature a.The receiving coil 0 is wound around both of the poles b, assing throughI the channels 6', a small anged strip 0,

shown in dotted lines in Fig. 2, serving to hold the winding in place. is

As shown in Fig. 2 the device is inclosed within the case-D carrying thediaphragm d which is attached to the vibrating reed A by means of thestud (1?. The case and diaphragm are removed in Fig, 1 in order "to showthe interior of the receiver.

It will be seen that the pull of the magne B upon'the reed A isurely-longitudinal,

so that a considerable orce can be exerted since the pull has notendency to deflect the reed and in fact maintains it ina cen-.

tralized position. On speech currentspasscoil C the maging-through thereceiving 2 in each of the magnet pole pieces 5 is disturbed andtransverse forces are set up which cause the reed to vibrate.

In the modification shown in Figs. 3 and 4 the magnet B is shown in theform of an electromagnet provided with the exciting coil 1), and thereed A is mounted at one end upon one pole b of the magnet, the magneticcircuit passing longitudinally through the reed to the opposite polepiece 5 on which the receiving coil C is wound, this pole piece having achannel b and gap 5 as in the previouscase. The end piece a of the reedis sufliciently deep to cover the gap 6 and a portion of the pole piece6 at each side of the gap, the end piece a being slotted in its face toreceive a number of small copper strips a. T 0 give flexibility to thereed it is formed with a neck a of reduced thickness, the thin neckportion being widened to prevent undue resistance to the magnetic flux.

The action of the device shown in Figs. 3 and 4 is very similar to thatshown in Figs. 1 and 2, the pole b exerting a considerable pull on thereed while the ellect of the speech currents through the coil C is tocause the reed to vibrate transversely.

In the modification shown in Fig. 5 the magnet is made with twoconcentric pole pieces I) and b both formed with a series of channels I)and gaps b. The reed A in this case consists of an arm carrying'at itsend a curved iron flange or strip a which projects into the gap betweenthe two poles b and b a small clearance only being al lowed on each sideof the flange a. The two receiving coils C are wound through the Y whichthe device is to be put.

channels I) and the reed flange a is divided by a series of copper orother non-magnetic conductors. The action of the poles I), b"

is to exert a radial pull upon the flange a. of the vibrating member orreed, which may be pivoted at the opposite end a while the transversevibrations are caused by speech currents in the coils C. The principleupon which this modification is constructed is therefore the same asthat embodied in the other forms already described.

As shown in Fig. 6 a receiving coil C or coils may be provided onthe'end of the reed A instead of or as well as on the magnet B, butusually the coil or coils would be placed on the magnet alone, wherethey are not subject to vibration. The reed may be connected to atelephone diaphragm as shown in Fig. 2 or as is obvious to a microphoneor other relay according to the use to Such con nections form no part ofthe present invention and are not illustrated.

hat I claim and desire to secure by Letters Patent of the United Statesis 1. In an electrical translating device as set forth, a magnet, avibratory member held at one end and having its free end closelyadjacentto a pole of the said magnet, whereby the magnet exerts a strongpermanent longitudinal pull on the said member, and a receiving coiladapted to act transversely upon the main magnetic field and to effectoscillation of the vibratory member, the permanentlongitudinal pullbeing large compared to the transverse forces due to the coil.

2. A device as claimed in claim 1, in which the aforesaid vibratorymember is in the form of a reed comprising a comparatively rigid flatstrip having a flexible hinge portion.

3. In an electrical translating device of the kind set forth, a magnet,a vibrating reed comprising a plurality of thin plates, a flexible hingestrip upon which the plates are mounted, and a small armature on theouter end of the said plates, the said reed having its end closelyadjacent to a pole of the magnet so that the latter exerts a substtgtialpermanent longitudinal pull on the re at. In an electrical translatingdevice of the kind set forth, a vibratory member, a permanent magnet thetwo poles of which are adjacent to the same end of the said member andexert a longitudinal pull on the said member and a receiving coiladapted to act transversely on the magnetic field.

5. In an electrical translating device of the kind set forth, avibratory member, a magnet having channeled pole pieces adjacent to thefree end of the vibratory member and adapted to exert a strong permanentpull longitudinally of the said member, and a receiving coil woundthrough the pole channels.

6. A telephone receiver comprising a vibratory member, a magnet having apole closely adapted to the free end of the said main magnetic field, adiaphragm and a connection between the diaphragm and the vibratorymember.

IDNEY GEORGE BROWN.

